Rotatable tremulant sound producer



Nov.'18, 1952 LESUE 2,618,352

ROTATABLE TREMULANT SOUND PRODUCER Filed June 13, 1949 INVENTOR. .D0M440 r7: LEsL/E,

TTOQNEY.

Patented Nov. 18, 1952 ROTATABLE TREMULANT SOUND PRODUCER Donald J. Leslie, Wilmar, Calif.

Application June 13, 1949, Serial No. 98,815

3 Claims. (Cl. 18127) The present invention relates to the production of musical tones, and is more particularly directed to apparatus or devices for imposing pitch tremolo or vibrato on musical tones.

This application is a continuation-in-part of an application filed in the name of Donald J. Leslie, Serial No. 603,850, filed July 9, 1945, for AcousticApparatus, now- Patent No. 2,489,653, which application is a continuation-in-part of an abandoned application filed in the name of Donald J. Leslie, Serial No. 369,413, filed December 10, 1940, for Acoustic Device.

The foregoing applications disclose the production of musical tones by electrical means, including a low frequency sound translating device and a high frequency sound translating device. A sound transmitting channel is associated with each device and vibrato effects are obtained by causing the mouths of these channels to rotate. During such rotation, the mouths move alternately toward and away from the listener or sound source at a frequency corresponding to the vibrato. In this manner, the pitch of the sounds heard by the listener is alternately increased and decreased.

-As set forth in the foregoing applications, proper vibrato effects are obtainable by movin each sound channel through which the sound passes cyclically between five and eight cycles per second, or at a speed of rotation of between about 300 and 480 revolutions per minute.

An object of the present invention is to provide an apparatus for imposing vibrato on sound, embodying rotatable and separate high frequency and low frequency sound translating devices and associated sound channels that are compactly arranged and occupy much less space than was heretofore necessary.

Another object of this invention is to provide an apparatus for imposing pitch tremolo or vibrato on sound, embodying separate rotating or movable low frequency and relatively high frequency sound channels, in which the sound is transmitted simultaneously through the channels in the same direction.

This invention possesses many other advantages, and has other objects which maybe made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description isnot to be taken in a limiting sense,

2 since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a vertical section through a portion of an apparatus embodying the invention;

Fig. 2 is a cross-section taken along the line 22 on Fig. 1; and

Fig. 3 is an enlarged vertical section through part of the high frequency speaker and horn portion of the apparatus.

As disclosed in the drawings, a base or low frequency speaker or sound generator I0, and a treble or high frequency speaker or sound generator II are housed within a cabinet I2. A directional horn I3 is associated with the low frequency speaker IE, and another directional horn I4 is operatively associated with the high frequency speaker II. These horns form sound channels I5, I6 having mouth or sound emitting openings I], I8 spaced from their common axis of rotation I9. The sound may pass from the horns I3, [4 outwardly of the cabinet through a number of openings 20 that may be covered by louvers, grilles, or with a light fabric material 2I In the form of invention disclosed in the drawings, the speakers I0, II and horns I3, I4 are coaxially arranged. The low frequency speaker I0 is disposed upon a low frequency cone 22, including the diaphragm 22a, that is suitably fastened to a platform or shelf 23 extending across the cabinet I2 above the cabinet openings 20. The high frequency speaker II, which is coaxial of the low frequency speaker, is suitably supported in a transverse bar 24 extending across a central opening 25 in the platform or shelf 23, through which the sound from the low frequency speaker and cone may pass.

The cabinet I2 is of such design as to prevent radiation from the back of the speaker cone 22a into the room. Thus, the cabinet can have a top or transverse partition I2a forming a complete enclosure I2b with the cabinet side walls I20, or it may be of the bass reflex design, with relief ports which radiate at low frequencies only. The purpose of the enclosure is to restrict radiated sounds to the front surface of the cone only, as this is the portion of the speaker radiation that is directed through the rotary horn I3.

The sound from the low frequency cone 22a passes through the opening 25 and through the throat 26 of the rotatable low frequency horn I3, which has its mouth or sound emitting opening I! spaced from the axis of rotation I9 of the horn. This horn defines the elbow-like sound channel I5 extending between its throat 26 and mouth H, to enable its direction of sound out- 7 wardly through the cabinet openings 20.

The sound from the high frequency speaker H passes into the throat or hub portion 21 of the rotatable high frequency horn [4. The high frequency horn is suitably secured in a hub member 23 fixed to and supported coaxially of the low frequency horn 13 by a plurality of radial spokes ZQj -eXtending across the low frequency. horn throat 26 to its outer portion. Thus, the

high frequency horn It is fixed to, and coaxially of, the low frequency horn is, with its mouth 18 facing in the same direction as the mouth ll of the low frequency horn [3. This latter mouth may be suitably covered by cloth 30 to reduce the effects of windage during rotation of the horn 13. If desired, a conical deflector 3| may be secured at the mouth portion is of the high'frequency horn It; so as to broaden the radiation to a shaft 32 rotatably supported ina suitable bearing 33 mounted on the base 34 ofthe-cabinet. The upper end of the rotor l3 and the high1fre-- quencyhorn It are rotatably supported by causingcthe throat 21 of the high frequency horn to rotate within a ball bearing 35. The inner race 36 of the bearing is secured on the throat 21, th bearing load being transmitted through suitable balls 38 to an outer race 39 mounted in a plate 49 that issuitably attached to the supporting bar 24, as by means of bolts 4|. The sound emanating from the high frequency speaker, H can pass through a central aperture 62 in the plate 49 into the throat 2! of the inner horn, l4.

The bearings 33, 35 are coaxial and also coaxial with the speakers 10, H and throats 26, 2! of the horns i3, 14. Accordingly, rotation of the low frequency horn l3 about the axis is will alsov effect rotation of the high frequency horn l4 about the axis. Such rotation may be pro vided by a suitable electric motor 43 attached to the cabinet l2 and having a drive pulley 44 for moving a belt 45 disposed over a driven pulley 46 mounted on the horn shaft 32. speed and diameters of the pulleys are so chosen as to, rotate both horns l3, [4 at the desired speed to impose pitch tremolo on the musical tones. emanating from the speakers H3, I l.

The apparatus is intended for use in connection with an electronic device, such as an electric organ (not shown). The final. amplifier stages of such a device may be connected with the speakers Hi, H by suitable; cables 41, in a conventional manner, through a suitable dividing network 48, which will limit the frequencies,

supplied to the respective speakers. Such dividing network 48 and the connections 4T- between the amplifier and high and low frequency speakers are, well understood by those skilled in the art, and need not be detailed in this specification.

The horns l3, 14 are rotated simultaneously by the electric motor 43 at the appropriate tremolo or vibrato speed, the sound from the low frequency speaker 18 and cone 2? passing through the low frequency sound channel l5 and outwardly through its opening 1L- similarly the,

The motor 7 sound is passing from the high frequency speaker I l and through the mouth 18 of its sound channel [6, which faces in the same direction as the mouth [1 of the other channel I5. By disposing one horn 14 Within the other I3, a compact arrangement is provided, necessitating only a single operating mechanism, such as the motor 43, for eifecting simultaneous rotation of the horns at the appropriate speed. At the same time, the high and low frequency notes are transmitted simultaneously in the same direction at any instant of time, the high frequency notes being appropriately superposed upon the low frequen'cy notes; as well as the vibrato effects from both notes.

Although the invention has been particularly described with respect to sound channels for directing sound from high and low frequency speakers, it is quite apparent that a similar arrangement may be used, for transmitting sound froma source into high and low frequency microphonesthat would be located --at the same. pg sitions as the speakers arelocated in the 'dra mgs.

second, the vibratoor tremolo effect willbe posed uponvthe several. tones entering the channelsv l5, I6.

The inventor claims;

1. In apparatus for adding tremolo to musical speakersurrounding the other opening; a mount ing for said speakers, the openings of the speakers. being substantiallycoaxial; a, pair; of; means defining sound channels each having, a; throat cooperating respectively with said speaker;- openings, said throatsbeingdocated one withinthe other, each soundchannel having n open,

ing for emittingsound;- means mountingboth said sound channel, definin means for:rotation about a common axis coaxial withthe: openings I of said speakers; and power means coupled tosaid sound channel, defining means to cause orbital motion. of said sound channelopeningsr 2. vIn apparatus for adding tremolo tomusical a pairof speakers adapted respectively to translate high and low frequency-sound waves; eachof said speakers having openings,

sounds:

the opening'of one ofthe speakers being-larger than the opening of; the other speaker; a mount-- ing for said speakers, the openings-of the speakers being substantially coaxial-'ymeansde fining a first sound channel having a throat communicable with the opening of said one speaker said first sound channel having an opening for emitting sound;-means defining a second soundlchannel' having a throat communicablewith" he an u n; her, s kcrrs i' s ce.

on'df sound channel having an opening for emitting soundg means mounting said second, sound channel defining means within said first.-

sound channel defining means; I means ,mountmotion; of: said sound channel openings.

3. In apparatusfor adding tremulant eifect toy at n e horns t the a ro r at speed of from about 300 to 480 revolutions per minute, or from about five to eight cycles per musical sounds: a high and a low frequency speaker having openings adapted respectively to translate high and low frequency sound waves; a support for said speakers mounting said high frequency speaker substantially within said low frequency speaker, the openings of the speakers being substantially coaxial and similarly directed; means forming a low frequency sound channel having a throat cooperable with the opening of said low frequency speaker; means mounting said low frequency sound channel forming means for angular movement about an axis substantially coaxial with the opening of said speakers, and mounting said channel to register said throat; with said low frequency speaker; said low frequency sound channel having an opening spaced from said axis; means forming'a high frequency sound channel having a throat cooperable with said high frequency speaker; means mounting said high frequency sound channel forming means within said low frequency sound channel forming means to register said throat of said high frequency channel forming means with said high frequency speaker; said high frequency sound channel forming means having an opening spaced from said axis; and power means coupled to said channel formin means for rotating said channels to impart an orbital motion to said sound channel openings.

DONALD J. LESLIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

